The goal of this NRSA F32 application is to identify subclasses of GABAergic interneurons in the piriform cortex of the olfactory system and determine their role in olfactory sensory information processing. The specific aims of this application are: Specific Aim 1. Identify a specific subclass of GABAergic interneurons in the piriform cortex that narrows the synaptic integration window of pyramidal cells. Specific Aim 2. Determine if the intrinsic microcircuitry in the piriform cortex produces regular oscillatory activity. Specific Aim 3. Test the hypothesis that the intrinsic oscillatory activity helps pyramidal cells "tune" to the extrinsic gamma frequency oscillatory mitral cell LOT input. To achieve the specific aims of this application, the experiments employ a combination of electrophysiological and calcium imaging techniques. It will involve studying both GABAergic interneurons directly with patch clamp and fura-2, AM imaging, as weii as indirectly, by studying their role in shaping the electrophysiological response of pyramidal cells to lateral olfactory tract and associational fiber stimulation. Specifically, I propose to study the intrinsic oscillatory behavior of the anterior piriform cortex microcircuitry, and its relationship to the olfactory bulb gamma frequency input. I plan to use the olfactory sensory system as a template to help understand how the nervous system is organized and how this organization facilitates the integration of sensory information. Identifying the different subclasses of GABAergic interneurons by employing electrophysiological and Ca2+imaging techniques may prove important in determining the basic principles of neural transmission in the olfactory system as well as other neural sensory systems. This information may be useful in developing new drugs and therapies for sensory and neurological disorders, diseases such as Alzheimer's and Parkinson's diseases that result in olfactory deficits.